Should You Use an Adjuvant [With Your Insecticides]?
Christelle Guedot, University of Wisconsin-Madison
Cranberry Crop Management Journal, Vol 33 (2): May 13, 2020

Adjuvants are products that are added to a pesticide to enhance the performance and/or physical properties of the pesticide. Adjuvants include, but are not limited to, surfactants, oils, defoaming agents, deposition agents, thickeners, spreaders, compatibility agents, and drift control agents, to name a few. Using the proper adjuvant may reduce, or even eliminate in some cases, spray application problems, thus improving the overall effectiveness of the pesticide. Adjuvants do not have any pesticidal properties by themselves and thus are not required to be registered by the U.S. EPA (Environmental Protection Agency), and their distribution is seldom regulated by states. However, adjuvants have labels that you should read and follow to avoid problems.

There are two main categories of adjuvants: the formulation adjuvants that are already mixed in with the pesticide you purchase and are part of the inert ingredients on the label, and the spray adjuvants that are separate products that you may need (per label direction) or decide to add to the spray tank. Here, we are discussing spray adjuvants. For more information on the different types of adjuvants, please refer to this article from PennState Extension.

There is an amazing number of adjuvants to choose from, and this can be overwhelming at times. In addition, not all adjuvants are alike and of the same quality. If you are looking for some kind of standard quality, look for the CPDA stamp of certification. CPDA stands for the Council of Producers and Distributors of Agrotechnology, which is an organization of inert ingredient and adjuvant manufacturers. This organization develops minimum standards to be met in order to receive the CPDA stamp of certification for adjuvants. Here is a list of certified adjuvants, and the following figure shows the stamp of certification from CPDA you can look for on adjuvant labels.

If you decide to use an adjuvant, please be sure to first check the label of the pesticide you plan to add the adjuvant to. Pesticide labels often have very specificf instructions on what type of adjuvant to use and how to use/mix it with the pesticide. You are required to follow these instructions to be in compliance with the law.

If you have questions about the specific properties of an adjuvant, you should contact the manufacturer or dealer of that product before using it. Adjuvants may cause phytotoxicity, may already be part of the pesticide formulation, may lead to unsafe interaction or improper mixing with some pesticides, and could cause harm to beneficial insects. We have conducted trials with a few surfactants to improve the effectiveness of insecticides and overall, the surfactants that we have tried did not significantly increase of the effectiveness of the insecticides we tried.

Take away. When considering adding an adjuvant, please remember to:

• Read the pesticide label
• Read the adjuvant label if available (remember, it is not reviewed by the EPA)
• Use only adjuvants manufactured and marketed for agricultural/horticultural use
• If the pesticide label specifies a type and/or brand name of adjuvant, you have to use that type and/or brand name. Any substitution would be a violation of the label.
• Miracle adjuvants do not exist. Look for products from a reputable dealer or for the CPDA stamp
• Pesticide formulations often change, which may change the adjuvant recommendations. Always read the pesticide label
• Adjuvants are not always useful. If the pesticide label does not mention using an adjuvant, it is likely because the manufacturer has data showing no benefit, or even adverse effect, from using adjuvants.

Spray adjuvants used according to the pesticide label can play an important role in safe and effective pest control. Make sure to know the site you plan to spray, the target pest, the mixing and spray equipment you will use, and the pesticide you plan to use to insure the correct use of an adjuvant. And always read the pesticide label for teh recommended adjuvant to use.